Digital content providers, including record labels and book publishers, lose a lot of money to piracy. Copyright protection technologies such as Digital Rights Management (“DRM”) of the Open Mobile Alliance (“OMA”) are safeguards to drive out content thieves in the digital era. DRM plays a role to take care of digital content from its birth throughout its life cycle by preventing illegal reproduction of the content.
DRM is a set of technologies that provide the means to control the distribution and consumption of the digital media objects. In typical implementations of DRM, a rights issuer (“RI”) grants a digital license, called a Rights Object (“RO”), to a device to consume a digital media content object (“CO”) according to a specific set of permissions. The permissions usually are specified by using a document specification language like XrML or other similar languages. Due to the extensive protection provided by DRM, it is utilized for various types of local area networks.
One type of local area network, namely a home network, is under one administrative domain. More particular, a home network is a collection of devices and sub-networks operated by a single organization or administrative authority. The components of the domain are assumed to interoperate with mutual trust among themselves, but interoperate with other domains in a less-trusted manner. This is to be contrasted with the network domain models, which maybe under multiple administrative domains.
A home network utilizes any technology or service that makes it possible to connect home devices to each other or automate them. A home networking device may be stationary or mobile, i.e., can leave or join the network at arbitrary times. Each device may also be turned on or off at various time. A more specific definition of a home network includes linking consumer electronic devices, computers, and peripherals within a home to form a connected environment. Home networking enables a family's electronic devices and household appliances to be connected to each other. These devices can also be seamlessly connected to the Internet, offering the advantage of an added content source. Internet access also provides this application's greatest threat, however, at least from the entertainment companies' viewpoint.
Some home networking applications rely on the existence of a home networking server to provide security for home networks. The server is responsible for storing content, managing keys for secure distribution of content to home devices, authenticating the home networking to content rights issuers, and managing and enforcing permissions. The server is usually a centralized device separate from other home devices. Servers are usually unwieldy devices that require complex configuration and setup. Further, being a centralized device, a server represents a possible single point of failure. If it fails, then the home networking cannot access any protected content. Further, consumers would be required to pay a significant amount for a device whose sole function is to manage other devices. Given these difficulties, a solution is needed that avoids the use of centralized servers.
Other home networking applications, such as the OMA DRM, require each home networking device to create a separate security association with media providers, i.e., entities that provide CO's and RO's. Thus, contacting media providers to obtain content incurs a storm of communication between the home network and the media provider. This storm needs to be repeated for every media server that the home network wants to access. Network servers are not required in the home network for these applications, and the applications use the ubiquitous public key infrastructure (“PKI”). However, the media provider would offer the services of a network server to the home network. The home networking devices must use these services, with the attendant loss of privacy for the home network.
Still other home networking applications use smart cards to enable home networking to interwork with any DRM scheme. For these applications, two cards are required: a Converter Card and a Terminal Card. The Converter Card decrypts RO's from RI's, translates the received permissions into a defined permission, re-encrypts the content encryption key by using a key that the Converter Card creates, sends the key securely to the Terminal Card, and sends the re-encrypted content encryption key to the Terminal Card. The Terminal Card decrypts the key and uses it to decrypt the content encryption key. Depending on the permissions, the Terminal Card may also need to issue challenges to the terminal on which the card resides.
Unfortunately, smart card-based applications have many weaknesses. All devices must have the capability to interface with smart cards, so there is no facility to include devices that do not support smart cards. The solution also assumes that all devices are fixed, so no extension is provided for wireless devices. Thus, there is no support for group management and no mechanism for authentication or authorization in remote domains. In addition, from a permissions point of view, these smart card-based applications are very limited. All permissions are mapped to a limited set of defined permissions, so RI's are limited in specifying the types of permissions offered to users.